When setting a custom workspace in a Freestyle project, the value is not saved in the configuration after clicking "Save" or "Apply". When reopening the configuration page, the option "Custom workspace" is no longer set.

Already existing Jobs which are configured with a custom workspace continue to work (the custom workspace is used during build), but re-configuring them will remove the setting and there seems to be no way to set it again (i have the config history plug-in installed and was able to restore the previous version, though)

Looking into config.xml shows that 

<customWorkspace>myWorksapce/</customWorkspace>

gets not set at all.